This invention relates generally to control levers used on machinery such as agricultural tractors to operate hydraulic devices and, more particularly, to a mechanism cooperable with the control lever to limit the movement thereof and, thereby, restrict the operation of the corresponding hydraulic device.
One rotatable control lever position control apparatus is disclosed in U.S. Pat. No. 4,548,094, issued to Thomas W. Huitema, et al, on Oct. 22, 1985. This apparatus is in the form of a cylinder having notches formed therein to engage the control lever passing therethrough and limit the movement of the control lever in accordance with the notch aligned with the control lever. The cylinder is provided with a thumb wheel member that projects upwardly through the control panel for rotation by the operator to select the respective notch to be aligned with the control lever.
It is desirable to provide an alternative control lever position control mechanism having a more positively engageable neutral lock to restrain the actuation lever in a neutral position to prevent accidental actuation of the corresponding hydraulics system. For example, the tractor could have an implement attached to the rear of the tractor and coupled to the remote hydraulic ports controlled by one of the actuation levers. Such a positive neutral lock would permit the transport of the implement without fear of engaging the operation of the implement during transport through an accidental bumping of the control lever in the operator's cab.
Such a control lever position control mechanism must also be operable through manipulation by the operator to limit the movement of the control lever in different selectable configurations to allow the operator to select the various modes of operation of the hydraulic system. Many hydraulic control levers are operable through four positions, raise, neutral, lower and float positions. The control lever position control mechanism can limit movement of the control lever to certain of these positions to correspond to traditional operations of the hydraulic system.